When PC Warnock is trying unsuccessfully to phone Dr Hume's wife, he says to Sergeant MacReady that "she's been engaged for over an hour now". However, just before Warnock hung up, the audible tone was that of a ringing telephone, not an engaged line.
PC Heggie changes into her uniform at home, then walks to work in it, instead of changing into it at the station. British police officers never do this, as it would make them and their families potential targets.
When Ralph Beswick the Teacher is looked up in the Prisoner manifest by the women constable you see his list of current and past charges on the first shot of the screen the red word CURRENT is across from history in the second shot it is in its correct spot across from the first Spousal assault you see on this list.
(at around 1h 13 mins) Cameraman is visible in the glass in the background, shortly after Sgt. MacReady shoots the shotgun into ceiling, as the camera pans around.
Ear plugs can been seen in one of the shotgun segments.